Oilfield application of solar energy collection

ABSTRACT

Solar energy is collected and used for various industrial processes, such as oilfield applications, e.g. generating steam that is injected downhole, enabling enhanced oil recovery. Solar energy is indirectly collected using a heal transfer fluid in a solar collector, delivering heat to a heat exchanger that in turn delivers heal into oilfield feedwater, producing hotter water or steam. Solar energy is directly collected by directly generating steam with solar collectors, and then injecting the steam downhole. Solar energy is collected to preheat water that is then fed into fuel-fired steam generators that in turn produce steam for downhole injection. Solar energy is collected to produce electricity via a Rankine cycle turbine generator, and rejected heat warms feedwater for fuel-fired steam generators. Solar energy is collected (directly or indirectly) to deliver heat to a heater-treater, with optional fuel-fired additional heat generation.

CROSS REFERENCE TO RELATED APPLICATIONS

Priority benefit claims for this application are made in theaccompanying Application Data Sheet, Request, or Transmittal (asappropriate, if any). To the extent permitted by the type of the instantapplication, this application incorporates by reference for all purposesthe following applications, all commonly owned with the instantapplication at the time the invention was made:

U.S. Provisional Application (Docket No. 310618-2001 and Ser. No.61/149,292), filed Feb 02, 2009, first named inventor Rod MacGregor, andentitled Concentrating Solar Power with Glasshouses;U.S. Provisional Application (Docket No. CLEN-002/00US 310618-2002 andSer. No. 61/176,041), filed May 06, 2009, first named inventor Peter VonBehrens, and entitled Concentrating PhotoVoltaics with Glasshouses;PCT Application (Docket No. GP-09-01PCT and Serial No. PCT/US10/22780),filed Feb. 01, 2010, first named inventor Roderick MacGregor, andentitled Concentrating Solar Power with Glasshouses;U.S. Provisional Application (Docket No. GP-10-02 and Ser. No.61/361,509), filed Jul. 05, 2010, first named inventor Peter VonBehrens, and entitled Concentrating Solar Power with Glasshouses;U.S. Provisional Application (Docket No. GP-40-04 and Se. No.61/361,512), filed Jul. 05, 2010, first named inventor John SetelO'Donnell, and entitled Direct Solar Oilfield Steam Generation;U.S. Provisional Application (Docket No. GP-10-04A and Ser. No.61/445,545), filed Feb. 23, 2011, first named inventor John SetelO'Donnell, and entitled Direct Solar Oilfield Steam Generation;U.S. Provisional Application (Docket No. GP-10-08 and Ser. No.61/361,507), filed Jul. 05, 2010, first named inventor John SetelO'Donnell, and entitled Oilfield Application of Solar Energy Collection;PCT Application (Docket No. GP-10-02PCT and Serial No PCT/US11/42891),filed Jul. 02, 2011, first named inventor Peter Von Behrens, andentitled Concentrating Solar Power with Glasshouses; andPCT Application (Docket No. GP-10-04APCT and Serial No. PCT/US11/42906),filed Jul. 03, 2011, first named inventor John Setel O'Donnell, andentitled Direct Solar Oilfield Steam Generation.

BACKGROUND Field

Advancements in solar energy collection and use thereof are needed toprovide improvements in performance, efficiency, and utility of use.

Related Art

Unless expressly identified as being publicly or well known, mentionherein of techniques and concepts, including for context, definitions,or comparison purposes, should not be construed as an admission thatsuch techniques and concepts are previously publicly known or otherwisepart of the prior art. All references cited herein (if any), includingpatents, patent applications, and publications, are hereby incorporatedby reference in their entireties, whether specifically incorporated ornot, for all purposes.

Concentrated solar power systems use minors, known as concentrators, togather solar energy over a large space and aim and focus the energy atreceivers that convert incoming solar energy to another form, such asheat or electricity. There are several advantages, in some usagescenarios, to concentrated systems over simpler systems that directlyuse incident solar energy. One advantage is that more concentrated solarenergy is more efficiently transformed to heat or electricity than lessconcentrated solar energy. Thermal and photovoltaic solar receiversoperate more efficiently at higher incident solar energy levels. Anotheradvantage is that non-concentrated solar energy receivers are, in someusage scenarios, more expensive than mirror systems used to concentratesunlight. Thus, by building a system with mirrors, total cost ofgathering sunlight over a given area and converting the gatheredsunlight to useful energy is reduced.

Concentrated solar energy, collection systems, in some contexts, aredivided into four types based on whether the solar energy isconcentrated into a line-focus receiver or a point-focus receiver andwhether the concentrators are single monolithic reflectors or multiplereflectors arranged as a Fresnel reflector to approximate a monolithicreflector.

A line-focus receiver is a receiver with a target that is a relativelylong straight line, like a pipe. A line-focus concentrator is areflector that receives sunlight over a two dimensional space andconcentrates the sunlight into a significantly smaller focal point inone dimension (width) while reflecting the sunlight withoutconcentration in the other dimension (length) thus creating a focalline. A line-focus concentrator with a line-focus receiver at its focalline is a basic trough system. The concentrator is optionally rotated inone dimension around its focal line to track daily movement of the sunto improve total energy capture and conversion.

A point-focus receiver is a receiver target that is essentially a point,but in various approaches is a panel, window, spot, ball, or othertarget shape, generally more equal in width and length than a line-focusreceiver. A point-focus concentrator is a reflector (made up of a singlesmooth reflective surface, multiple fixed facets, or multiple movableFresnel facets) that receives sunlight over a two-dimensional space andconcentrates the sunlight into a significantly smaller focal point intwo dimensions (width and length). A monolithic point-focus concentratorwith a point-focus receiver at its focal point is a basic dishconcentrated solar system. The monolithic concentrator is optionallyrotated in two dimensions to rotate its focal axis around its focalpoint to track daily and seasonal movement of the sun to improve totalenergy capture and conversion.

A parabolic trough system is a line concentrating system using amonolithic reflector shaped like a large half pipe. The reflector has a1-dimensional curvature to focus sunlight onto a line-focus receiver orapproximates such curvature through multiple facets fixed relative toeach other.

A concentrating Fresnel reflector is a line concentrating system similarto the parabolic trough replacing the trough with a series of mirrors,each the length of a receiver, that are flat or alternatively slightlycurved in their width. Each mirror is individually rotated about itslong axis to aim incident sunlight onto the line-focus receiver.

A parabolic dish system is a point concentrating system using amonolithic reflector shaped like a howl. The reflector has a2-dimensional curvature to focus sunlight onto a point-focus receiver orapproximates such curvature through multiple flat or alternativelycurved facets fixed relative to each other.

A solar power tower is a point concentrating system similar to theparabolic dish, replacing the dish with a 2-dimensional array of mirrorsthat are flat or alternatively curved. Each minor (heliostat) isindividually rotated in two dimensions to aim incident sunlight onto apoint-focus receiver. The individual mirrors and an associated controlsystem comprise a point-focus concentrator whose focal axis rotatesaround its focal point.

In solar thermal systems, the receiver is a light to heat transducer.The receiver absorbs solar energy. transforming it to heat andtransmitting the heat to a thermal transport medium such as water,steam, oil, or molten salt. The receiver converts solar energy to heatand minimizes and/or reduces heat loss due to thermal radiation.

SYNOPSIS

The invention may be implemented in numerous ways, including as aprocess, an article of manufacture, an apparatus, a system, and acomposition of matter. In this specification, these implementations, orany other form that the invention may take, may be referred to astechniques. The Detailed Description provides an exposition of one ormore embodiments of the invention that enable improvements inperformance, efficiency, and utility of use in the field identifiedabove. The Detailed Description includes an Introduction to facilitatethe more rapid understanding of the remainder of the DetailedDescription. As is discussed in more detail in the Conclusions, theinvention encompasses all possible modifications and variations withinthe scope of the issued claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates various details of an embodiment of an oilfieldapplication of solar energy collection.

FIG. 2 illustrates various details of continuous constant-rate steaminjection via hybrid gas-solar steaming.

FIG. 3 illustrates various details of continuous variable-rate steaminjection via hybrid gas-solar steaming.

FIG. 4 illustrates various details of an embodiment of a solar heatedheater-treater.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures illustrating selecteddetails of the invention. The invention is described in connection withthe embodiments. The embodiments herein are understood to be merelyexemplary, the invention is expressly not limited to or by any or all ofthe embodiments herein, and the invention encompasses numerousalternatives, modifications, and equivalents. To avoid monotony in theexposition, a variety of word labels (including but not limited to:first, last, certain, various, further, other, particular, select, some,and notable) may be applied to separate sets of embodiments; as usedherein such labels are expressly not meant to convey quality, or anyform of preference or prejudice, but merely to conveniently distinguishamong the separate sets. The order of some operations of disclosedprocesses is alterable within the scope of the invention. Wherevermultiple embodiments serve to describe variations in process, method,and/or features, other embodiments are contemplated that in accordancewith a predetermined or a dynamically determined criterion performstatic and/or dynamic selection of one of a plurality of modes ofoperation corresponding respectively to a plurality of the multipleembodiments. Numerous specific details are set forth in the followingdescription to provide a thorough understanding of the invention. Thedetails are provided for the purpose of example and the invention may bepracticed according to the claims without some or all of the details.For the purpose of clarity, technical material that is known in thetechnical fields related to the invention has not been described indetail so that the invention is not unnecessarily obscured.

INTRODUCTION

This introduction is included only to facilitate the more rapidunderstanding of the Detailed Description; the invention is not limitedto the concepts presented in the introduction (Including explicitexamples, if any), as the paragraphs of any introduction are necessarilyan abridged view of the entire subject and are not meant to be anexhaustive or restrictive description. For example, the introductionthat follows provides overview information limited by space andorganization to only certain embodiments. There are many otherembodiments, including those to which claims will ultimately be drawn,discussed throughout the balance of the specification.

Thermal techniques for enhanced oil recovery enable improvements forcurrent and future oil production around the world. For example, steaminjection provides nearly half of California's oil production, andimprovements in ongoing expansion of steamflood and steam stimulationsystems enable a more nearly stable energy supply.

Injected steam expands oil production through several mechanisms. Byraising the temperature of oil and the surrounding formation, viscosityof the oil is reduced, thus expediting its flow. In some embodiments,steam flow and resulting condensed water flow sweep oil along towardsproduction wells. Other characteristics, such as reservoir pressure androck wettability, are affected by steam injection as well.

In some embodiments, steam used in oilfield operations is injected attemperatures ranging from 300F to 700F or 750F, and pressures at up to1500 or 2500 PSI, where particular temperatures and pressures aredetermined by specifics of the oil formation and production approach. Insome embodiments, steam for oilfield injection is produced inonce-through steam generators. In some embodiments, the steam generatorsare heated by fuel combustion. Fuel combustion carries many costs, suchas the cost of fuel, the costs of complying with regulatory regimesregarding air quality and disposal of combustion products, and comingregimes that impose costs for emitting CO2. In some embodiments,solar-heated steam generators are used to produce steam for oilfieldoperations. Solar-heated steam generators use little or no fuel, andthus emit little or no combustion products or CO2.

In some embodiments, point-focus “power tower” steam generation basedsolar apparatus systems deliver steam into an oilfield via a “reboiler.”a heat exchanger that condenses high-purity, high-pressure steam that isgenerated by the solar apparatus, and heat feed water or generate steamusing lower-purify oilfield feed water. In some embodiments, a limitedamount of solar steam as a percentage of daytime oilfield steam is used;small solar collectors feeding energy into lame steam distributionsystems make little difference in total flow rate. In some embodimentsand/or usage scenarios, one or more of the techniques described herein,such as solar steam injection and automatic control systems, enablehigher fractions of solar steam use, in some situations, extending above90% in both daytime and annual steam use. In some embodiments and/orusage scenarios, one or more of the techniques described herein enableline-focus solar collectors for oilfield steam generation that arerelatively lower cost than some power tower solar apparatus basedimplementations.

Solar energy is collected and used for various oilfield applications.Collected solar energy is used to generate steam to teed an industrialprocess, such as downhole injection, enabling enhanced oil recovery.Solar energy is optionally indirectly collected using a heat transferfluid in a solar collector. The heat transfer fluid delivers heat to aheat exchanger (such as a tube-in-tube heat exchanger) that in turndelivers heat into oilfield feed water, producing hotter water or steam.Solar energy is optionally directly collected by directly generatingsteam with solar collectors, and then injecting the steam downhole.Solar energy is optionally collected and used to preheat water that isthen fed into fuel-fired steam generators that in turn produce steam fordownhole injection. Solar energy is optionally collected and used toproduce electricity via a Rankine cycle turbine generator, and rejectedheat warms feed water for fuel-fired steam generators. Solar energy isoptionally collected and used (directly or indirectly) to deliver heatto a heater-treater, with optional fuel-fired additional heatgeneration.

Injection of Solar Steam for Enhanced Oil Recovery Applications

In some embodiments, “steamflood” operations involve a pattern ofmultiple steam injection wells and multiple oil production wells,arranged so that injected steam causes increased production at theproducer wells. While a “five-spot” pattern is common, many otherarrangements of injection and production wells are contemplated usingtechniques taught herein. In some embodiments, “huff-and-puff” or“cyclic stimulation” steam injection operations involve periodicallyinjecting steam into each well for a period of one or inure days, thenshutting steam supply to the well and producing oil from the well for aperiod of one or more weeks. In some embodiments, a steam distributionsystem of piping and flow control devices interconnects one or moresteam generators to a plurality of steam injection wells that operateconcurrently, in a steamflood configuration, a cyclic stimulationconfiguration, or some other suitable configuration. In someembodiments, applicable to “steamflood”, “cyclic stimulation”, and othersuitable configurations of oilfield steaming, a plurality ofconcentrating solar thermal collectors gather solar energy for steamgeneration. Solar reflectors track the sun and direct solar radiation tothermal energy receivers, that directly or indirectly heat water andgenerate steam that is fed into the steam distribution system andinjected downhole. In some embodiments, solar-generated steam providesthe majority of total steam supply for the injection, and injection ratevaries based on currently available sunshine. In some embodiments of“solar majority” steam injection, fuel-fired steam generators operate atnight and during other periods of low solar radiation to provide enoughsteam to maintain temperature of the steam injection system and wellsabove ambient temperature, without contributing significant steam flowinto the formation. In some embodiments of “solar majority” injection,fuel-fired steam generators operate continuously, providing a portion ofdaytime steam injection and continuing overnight and during periods oflow solar radiation to maintain system temperature at lower flow rates.

FIG. 1 illustrates various details of an embodiment of an oilfieldapplication of solar energy collection. In some embodiments, solar steamgenerators 38 are interconnected to steam distribution system 7 thatalso is supplied with steam from fuel-fired steam generators 9, andsolar heat provides a portion of steam supply. In some embodiments,solar-generated steam provides a large portion of daytime steam. In someembodiments, an automatic control system (not illustrated) thatautomatically communicates with solar field controls and controls forfuel-fired steam generators, enables solar heat to provide a largeportion of daytime steam.

FIG. 2 illustrates various details of a continuous constant-rate steaminjection embodiment and/or mode of operation of the automatic controlsystem. A “balancing” control unit (that is part of the automaticcontrol system) communicates with solar field controls and issuescommands to fuel-fired steam generator units, so that as solar steamoutput rate 10 c rises, the firing rate in fuel-fired generators isadjusted downwards lowering fuel-generated steam rate 12 c to maintaindesired total steam injection rate 11 c. In some embodiments, thedesired steam infection rate is nearly constant day and night, with flowrate varying approximately 10% about a target rate.

FIG. 3, illustrates various details of a continuous variable-rate steaminjection embodiment and/or mode of operation of the automatic controlsystem that provides control of fuel-fired generators to enable overallsteam injection rate 11 v to vary as much as 50% from an “average” steaminjection rate 13. Note in that as illustrated in FIG. 3, overall steaminjection rate 11 v is enabled to vary an hourly basis depending onsolar steam rate 10 v; in this mode of operation, solar energy is thusenabled to deliver a higher fraction of total daily steam productionthan in the constant-rate case illustrated in FIG. 2. In some usagescenarios, not illustrated, automated “turndown” of fuel firing ratesand feed water rates in fuel-fired generators producing variablefuel-generated steam rates 12 v, enables solar steam 10 v to deliver upto 100% of daytime steam flow while maintaining any desired total steamflow pattern.

In some embodiments, fuel-fired generator turndown strategy is designedto minimize annual cost of maintaining fuel burners and provingcompliance with applicable standards for emissions of criteriapollutants. Solar radiation varies continuously, rising smoothly ordiscontinuously from dawn until noon. In some embodiments, an oilfieldsteam distribution system has multiple fuel-fired steam generatorsinterconnected to a common steam distribution system. In someembodiments, to reduce or minimize a number of burner operating pointsto be measured and witnessed by regulatory authorities, a control systemturns down burners by fixed amounts, to two or three fixed firingpoints; “full” and “minimum”, or “full,” “medium,” and “minimum” firingrates. In an operating regime for a solar steam generation system withapproximately constant steam flow, as solar radiation and solar-firedsteam production changes, individual fuel-fired burners areautomatically commanded to move from “full” to “minimum”, or “full” to“medium” and then “medium” to “minimum”. By independently automaticallycontrolling multiple fuel-fired burners, the control system deliversapproximately constant steam flow rates. In some embodiments, oilfieldcontrol systems alter an order that fuel-fired generators are commandedto turn down as solar radiation rises, or an order that fuel-firedgenerators are ordered to return to full output as solar radiationfalls, to reduce or minimize operating costs. In some embodiments and/orusage scenarios, some steam generators are more efficient in fuelcombustion than others and some steam generators experience highermaintenance costs associated with varying fuel firing rates. The controlsystem's ordering of generator firing commands is implemented takinginto account the characteristics of particular steam generators.

Indirect Steam Generation for Enhanced Recovery Applications

In some embodiments of solar steam generation for enhanced oil recovery,solar heat is collected using a heat transfer fluid that gathers heat insolar collectors and delivers heat to a heat exchanger. The heatexchanger delivers heat into oilfield feed water, producing hotter wateror steam that in turn is fed into an oilfield feed water or steamdistribution system. In some embodiments of indirect steam generation,the heat transfer fluid is a synthetic oil, such as Therminol orDowtherm. In some embodiments of indirect steam generation, the heattransfer fluid is a blend of inorganic salts that circulate as moltensalt. In some embodiments of indirect steam generation, the heattransfer fluid is high-purity pressurized water that circulates andboils in a solar field and condenses in the heat exchanger.

Tube-in-Tube Heat Exchanger for Indirect Solar Steam Generation forEnhanced Oil Recovery Applications

In some embodiments of indirect solar steam generation, a heat exchangeris designed as a “tube-in-tube” type exchanger, where an interior tubecarries high-pressure oilfield feed water that is being converted tosteam, and an outer tube carries a heat transfer fluid heated by solarcollectors. Because liquid water is evaporated as it proceeds throughsteam generator piping, residual contaminants carried in feed waterconcentrate as liquid volume drops, progressively rising as liquidconverts to vapor phase. The term “steam quality” refers to thepercentage of inlet water mass that has been converted to vapor phase;thus 70% steam quality would have only 30% of original water in liquidphase, and contaminants would be concentrated by more than threefoldfrom the original feed water.

In some embodiments, an ideal oilfield steam generator delivers thehighest possible steam quality for a given feed water quality. Highersteam quality delivers more energy per pound of water injected. However,if steam quality exceeds limits imposed by water contaminantconcentration, corrosion and scaling begin to occur at unacceptably highrates, causing fouling, plugging, and potential failure or burnout ofsteam generator tubing. In some embodiments, economical operation occurswhen steam quality is tightly controlled, such as within a 5% to 10%range. In sonic embodiments and/or usage scenarios, a serpentinehorizontal arrangement of tube-in-tube apparatus enables economicaloperation, due in part to an extended horizontal boiling zone thatlimits mineral deposits, and in part to a capability to periodicallyclean collection tube interiors with acids and mechanical scrubbersknown as “pigs”.

In some embodiments, fuel-fired steam generators maintain steam qualitywithin a desired range by measuring inlet air and water temperatures,and controlling fuel firing rate and water feed rate appropriately. Insome embodiments, a tube-in-tube heat exchanger for indirect solar steamgeneration measures incoming heat transfer fluid temperature and flowrate. Automatic controls adjust inlet valves and pumps as well as outletvalves to manage outlet steam quality by modulating feed water flow in amanner proportional to heat carried in a heat transfer fluid. Automaticcontrols shut a steam outlet valve when heat flow from a solar field isinadequate to make target steam quality. A control system for thetube-in-tube heat exchanger communicates with a master control and/ordirectly with controls for other fuel-fired steam generators (such asdescribed above) to maintain overall desired steam flow rates.

Direct Steam Generation for Enhanced Oil Recovery Applications

In some embodiments of solar steam generation for enhanced oil recovery,oilfield feed water is fed directly into solar collectors, in anarrangement similar to a feed water system for fuel-fired steamgenerators, and as se alar heat is collected, the collected solar heatdirectly generates steam that in turn is fed into an oilfield feed wateror steam distribution system. In some embodiments and/or usagescenarios, line-focus solar collectors enable economical operation inoilfield steam generators, due in part to an extended horizontal boilingzone that limits mineral deposits, and in part to a capability toperiodically clean collection tube interiors with acids and mechanicalscrubbers known as “pigs”.

Solar Water Preheating for Enhanced Oil Recovery Applications

In some embodiments of solar steam generation for enhanced oil recovery,oilfield feed water is fed directly into solar collectors, and is raisedin temperature by solar heat without boiling (without conversion fromliquid to vapor phase). The heated water is then fed from solarcollectors into one or more fuel-fired steam generators. In someembodiments, a contribution of solar heat increases a rate of steamproduction by a fuel-fired steam generator for constant fuel firingrate. In some embodiments, a contribution of solar heat reduces a fuelfiring rate for a fuel-fired steam generator while maintaining aconstant steam production rate.

Solar Cogeneration of Heat and Electric Power for Enhanced Oil RecoveryApplications

In some embodiments of solar water preheating for enhanced oil recovery,oilfield water is directly heated via circulation in solar collectors.In some embodiments, oilfield water is preheated via a heat exchanger ina “solar cogeneration” configuration. In some cogeneration embodiments,solar collectors gather solar heat that drives a Rankine cycle turbinegenerator. Rejected heat from the Rankine generator warms feed waterthrough a heat exchanger, feeding the warmed feed water to one or morefuel-fired steam generators. In some embodiments, a heat transfer fluidflows through a solar field, and generates high-purity high-pressurevapor in a heat exchanger. In some, embodiments, a solar field directlygenerates high-purity, high-pressure vapor to drive a turbine. The highpressure vapor runs a Rankine cycle turbine. Turbine exhaust iscondensed in a heat exchanger, giving up latent heat of vaporization tooilfield feed water flowing through the heat exchanger. In someembodiments, vapor/liquid in a Rankine cycle turbine is steam/water. Insome embodiments, vapor/liquid in the Rankine cycle turbine is anorganic fluid such as toluene or pentane. In some embodiments, heattransfer fluid flowing through a solar field is a synthetic oil such asTherminol or Dowtherm. In some embodiments, heat transfer fluid flowingthrough a solar field is a molten salt mixture. In some embodimentsand/or usage scenarios, a configuration where a solar field directlygenerates high-pressure high-purity steam that flows through a steamturbine, producing electric power, and is condensed in a heat exchangerthat heats oilfield steam generator feed water, is implemented with areduced or lowest cost compared to other implementations.

Solar Heating for Produced Oil Treatment

In some embodiments, product flowing from oil wells is a mixture ofpetroleum, water, gas, and various contaminants. Separating oil andwater economically is desirable, in some usage scenarios. In someembodiments, such as illustrated in FIG. 4, “heater-treater” units 14separate oil 16, water 20, and gas 19, using a combination of chemicalsand heat to break oil-water emulsions. The heater-treater units, in someembodiments, comprise one or more of drain 21, mist extractor 22, gasequalizer 23, and during operation in some scenarios contain oil/waterinterface 24. In some embodiments, firetube heaters 17 are used inheater-treaters, delivering heat front fuel combustion into anoil-water-gas mixture. In some embodiments, a plurality of concentratingsolar thermal collectors (e.g. solar steam generators 38) gather solarenergy as heat. Solar reflectors 16 track the sun and direct solarradiation to thermal energy receivers that directly or indirectlyprovide heat to one or more heater-treater units. In some embodiments,heat transfer fluid circulates, gathering heat in a solar field, anddelivers the gathered heat into a heater-treater via heat exchanger tubeelement 18. In some embodiments, the heat transfer fluid is a syntheticoil such as Therminol or Dowtherm. In some embodiments, the heattransfer fluid is a molten salt mixture. In some embodiments,pressurized water is circulated in a solar field, delivering heat assteam that is recondensed in a heat exchanger tube in a heater-treater.In some embodiments, solar oil heat treatment optionally operatesintermittently, using solar radiation as available. In some embodiments,a heater-treater unit optionally includes a fuel burner (such asfiretube heaters 17) as well as a solar heat exchanger, enabling theheater-treater unit to operate continuously, with solar energy providinga portion of annual energy. In some embodiments (not illustrated), athermal energy storage system collects solar heat during the day andprovides extended-hour or continuous heat delivery to a heater-treaterunit, enabling continuous operation without fuel combustion.

CONCLUSION

Certain choices have been made in the description merely for conveniencein preparing the text and drawings and unless there is an indication tothe contrary the choices should not be construed per se as conveyingadditional information regarding structure or operation of theembodiments described. Examples of the choices include: the particularorganization or assignment of the designations used for the figurenumbering and the particular organization or assignment of the elementidentifiers (the callouts or numerical designators, e.g.) used toidentify and reference the features and elements of the embodiments.

The words “includes” or “including” are specifically intended to beconstrued as abstractions describing logical sets of open-ended scopeand are not meant to convey physical containment unless explicitlyfollowed by the word “within.”

Although the foregoing embodiments have been described in sonic detailfor purposes of clarity of description and understanding, the inventionis not limited to the details provided. There are many embodiments ofthe invention. The disclosed embodiments are exemplary and notrestrictive.

It will be understood that many variations in construction, arrangement,and use are possible, consistent with the description, and are withinthe scope of the claims of the issued patent. The names given toelements are merely exemplary, and should not be construed as limitingthe concepts described. Also, unless specifically stated to thecontrary, value ranges specified, maximum and minimum values used, orother particular specifications, are merely those of the describedembodiments, are expected to track improvements and changes inimplementation technology, and should not be construed as limitations.

Functionally equivalent techniques known in the art are employableinstead of those described to implement various components, sub-systems,operations, functions, or portions thereof.

The embodiments have been described with detail and environmentalcontext well beyond that required for a minimal implementation of manyaspects of the embodiments described. Those of ordinary skill in the artwill recognize that some embodiments omit disclosed components orfeatures without altering the basic cooperation among the remainingelements. It is thus understood that much of the details disclosed arenot required to implement various aspects of the embodiments described.To the extent that the remaining elements are distinguishable from theprior art, components and features that are omitted are not limiting onthe concepts described herein,

All such variations in design are insubstantial changes over theteachings conveyed by the described embodiments. It is also understoodthat the embodiments described herein have broad applicability to otherapplications, and are not limited to the particular application orindustry of the described embodiments. The invention is thus to beconstrued as including all possible modifications and variationsencompassed within the scope of the claims of the issued patent.

1-26. (canceled)
 27. An oil recovery system, comprising: a solarcollector, including: a reflector positioned to receive and redirectsolar radiation; and a receiver positioned to receive radiationredirected by the reflector; a turbine generator having an inlet and anoutlet, the inlet being thermally coupled to the receiver to receiveheat collected at the receiver; a heat exchanger thermally coupled tothe outlet and to a source of feed water to transfer heat from theoutlet to the feed water; a fuel-fired steam generator operativelycoupled to the heat exchanger to heat the feed water; and a steamdistribution system operatively coupled to the fuel-fired steamgenerator to receive steam from the fuel-fired steam generator, thesteam distribution system being coupled to at least one oilfield steaminjection well.
 28. The system of claim 27, further comprising a heattransfer fluid carried by the receiver and wherein the inlet of theturbine generator is coupled to the receiver to receive the heattransfer fluid.
 29. The system of claim 28 wherein the heat transferfluid includes water.
 30. The system of claim 27 wherein the heatexchanger is a first heat exchanger, and wherein the system furthercomprises: a first heat transfer fluid carried by the receiver; a secondheat transfer fluid carried by the turbine generator; and a second heatexchanger coupled between the receiver and the turbine generator totransfer heat from the first heat transfer fluid to the second heattransfer fluid.
 31. The system of claim 30 wherein the first heattransfer fluid includes a synthetic oil.
 32. The system of claim 30wherein the first heat transfer fluid includes a molten salt.
 33. Thesystem of claim 30 wherein the second heat transfer fluid includes anorganic fluid.
 34. The system of claim 27 wherein the turbine generatoris a Rankine cycle generator.
 35. The system of claim 27 wherein thereflector includes a parabolic trough reflector, and wherein thereceiver incudes an elongated conduit.
 36. A method for extracting oil,comprising: concentrating solar energy to generate heat; directing atleast a first portion of the heat to a turbine generator; rejecting atleast a second portion of the heat from the turbine generator; heatingfeed water with at least some of the second portion of the heat rejectedfrom the turbine generator; further heating the feed water with a fuelfired steam generator; and directing the further heated feed water to atleast one oilfield injection well.
 37. The method of claim 36 whereinconcentrating solar energy includes focusing the solar energy with aparabolic trough reflector onto a linear conduit.
 38. The method ofclaim 36 wherein directing at least the first portion of the heat to theturbine generator includes directing a heat transfer fluid from a solarcollector into the turbine generator.
 39. The method of claim 36 whereinthe heat transfer fluid includes water.
 40. The method of claim 36wherein directing at least the first portion of the heat to the turbinegenerator includes: directing a first heat transfer fluid from a solarconcentrator to a heat exchanger; transferring heat from the first heattransfer fluid to a second heat transfer fluid at the heat exchanger;and directing the second heat transfer fluid into the turbine generator.41. The method of claim 40 wherein the first heat transfer fluidincludes a synthetic oil.
 42. The method of claim 40 wherein the firstheat transfer fluid includes a molten salt.
 43. The method of claim 40wherein the second heat transfer fluid includes an organic liquid. 44.The method of claim 36 wherein heating feed water with at least some ofthe second portion of the heat rejected from the turbine generatorincludes heating the feed water at a heat exchanger.
 45. An oil recoverysystem, comprising: a solar collector, including: a reflector positionedto receive and redirect solar radiation; and a receiver positioned toreceive radiation redirected by the reflector; and a heater-treater unitcoupled to the solar collector to receive heat from the solar collector.46. The system of claim 45 wherein the heater-treater unit is configuredto heat constituents of a fluid mixture extracted from an oil fieldduring an enhanced oil recovery operation, and wherein the systemfurther comprises a steam distribution system operatively coupled to atleast one oilfield production well to receive the fluid mixture anddirect the liquid mixture to the heater-treater unit.
 47. The system ofclaim 45, further comprising a fuel-fired heater coupled to at least oneof the heater-treater or the solar collector to supplement heatgenerated by the solar collector.
 48. The system of claim 47 wherein thefuel-fired heater includes a firetube heater.
 49. The system of claim45, further comprising a heat transfer fluid carried by the receiver andwherein the heater-treater unit is coupled to the receiver to receivethe heat transfer fluid.
 50. The system of claim 49 wherein the heattransfer fluid includes water.
 51. The system of claim 45, furthercomprising: a first heat transfer fluid carried by the receiver; asecond heat transfer fluid carried by the heater-treater unit; and aheat exchanger coupled between the receiver and the heater-treater unitto transfer heat from the first heat transfer fluid to the second heattransfer fluid.
 52. The system of claim 51 wherein the first heattransfer fluid includes a synthetic oil.
 53. The system of claim 51wherein the first heat transfer fluid includes a molten salt.
 54. Thesystem of claim 51 wherein the second heat transfer fluid includes anorganic fluid.
 55. The system of claim 45, further comprising a thermalenergy storage system coupled to the solar collector to store heatgenerated by the solar collector.
 56. A method for processing extractedoil, comprising: concentrating solar energy via a solar collector togenerate heat; and directing at least one portion of the heat to aheater-treater unit.
 57. The method of claim 56, further comprising:directing an oil-containing mixture from an oil extraction well to theheater-treater unit; and at the heater-treater unit, separating oil fromthe oil-containing mixture using the at least one portion of heat 58.The method of claim 57 wherein separating includes separating the oilfrom water.
 59. The method of claim 57 wherein separating includesseparating the oil from a gas.
 60. The method of claim 57, furthercomprising heating the oil-containing mixture with a fuel-fired heater.61. The method of claim 57, further comprising storing at least some ofthe heat generated at the solar collector, at a thermal energy storagesystem.
 62. The method of claim 57 wherein separating oil from theoil-containing mixture is performed without combusting fuel to heat theoil-containing mixture.